1. Field of the Invention
The present invention relates to a method for manufacturing a head chip which is mounted on an ink-jet type recording apparatus applicable to, for example, a printer and a facsimile.
2. Description of the Related Art
Conventionally, an ink-jet type recording apparatus is known in the technical field, in which a recording head for jetting ink droplets from a plurality of nozzles is employed to record characters and/or images on a recording medium. In such an ink-jet type recording apparatus, the recording head positioned opposite to the recording medium is provided on a head holder, and this head holder is mounted on a carriage so as to be scanned along a direction perpendicular to a transport direction of the recording medium.
In FIG. 12, there is shown an exploded/perspective view of one example of such a recording head. FIGS. 13A and 13B are sectional view of a major portion of this recording head. FIG. 13A is a sectional view of the recording head taken along the longitudinal direction of side walls. FIG. 13B is a sectional view of the recording head taken along the thickness direction of side walls. A plurality of grooves 102 are arranged in a piezoelectric ceramic plate 101 in a parallel manner. The respective grooves 102 are separated from each other by side walls 103. One end portion of each of the grooves 102 in the longitudinal direction is elongated up to one end surface of the piezoelectric ceramic plate 101, whereas the other end portion is not elongated up to the other end surface of this piezoelectric ceramic plate, and a depth thereof gradually becomes shallow. Also, an electrode 105 used to apply a driving electric field is formed on surfaces of both the side walls 103 on the opening side within each of the grooves 102 along the longitudinal direction.
A cover plate 107 is jointed via an adhesive agent 109 to the grooves 102 of the piezoelectric ceramic plate 101 on the opening side. This cover plate 107 has an ink chamber 111 that constitutes a concave portion which is communicated to the shallow other end portion of each of the grooves 102 and an ink supply port 112 that is penetrated through a bottom portion of this ink chamber 111 along a direction opposite to the direction of the grooves 102.
A nozzle plate 115 is jointed on an end surface of a joint member made by the piezoelectric ceramic plate 101 and the cover plate 107, at which the grooves 102 are opened. Nozzle openings 117 are formed in the nozzle plate 115 at such positions located opposite to the respective grooves 102.
It should be noted that a wiring board 120 is fixed on such a surface of the piezoelectric ceramic plate 101, which is located opposite to the nozzle plate 115 and also opposite to the cover plate 107. A wiring line 122 which is electrically connected to each of the electrodes 105 by employing a bonding wire 121 or the like is formed on the wiring board 120. A driver voltage may be applied via this wiring line 122 to the electrode 105.
In the recording head constituted in this manner, when ink is filled from the ink supply port 112 into the respective grooves 102 and a predetermined driving electric field is applied via the electrode 105 to the side walls 103 on both sides of a predetermined groove 102, the side walls 103 are deformed, so that a capacity formed within this predetermined groove 102 is change. As a result, the ink filled inside the grooves 102 may be jetted from the nozzle opening 117.
For example, as shown in FIG. 14, in the case where ink is jetted from a nozzle opening 117 corresponding to a groove 102a, a positive driving voltage is applied to both electrodes 105a and 105b provided in the groove 102a, and also electrodes 105c and 105d located opposite to these electrodes 105a and 105b are grounded. As a consequence, a driving electric field directed to the groove 102a is effected to the side walls 103a and 103b. When this driving electric field is positioned perpendicular to the polarization direction of the piezoelectric ceramic plate 101, both the side walls 103a and 103b are deformed along the direction of the groove 102a due to the piezoelectric thickness slip effect, so that the capacity defined inside the groove 102a is reduced to there by increase pressure. Thus, the ink may be jetted from the nozzle opening 117.
However, since such a head chip employs a large amount of high-cost ceramic, there is a problem in that the manufacturing cost of the head chip is high.
To solve such a problem, Japanese Patent Examined Publication No. Hei 6-6375 has proposed such a head chip which is manufactured by the plate shaped board made of glass, piezoelectric ceramic plate made by arranging the pressure chambers in the array form on this plate-shaped board, and ink chamber plate made of glass.
In accordance with this head chip, since both the plate-shaped board and the ink chamber plate are made of low-cost glass materials, this head chip can be manufactured in low cost and also the manufacturing time can be shortened.
However, the above-explained head chip with employment of the glass board owns such a problem in that since the electrode for applying the voltage to the piezoelectric ceramic plate has to be formed by way of the oblique vapor deposition, the manufacturing cost is increased.
Also, when the wiring lines electrically conducted to this electrode are extracted, these wiring lines are processed by metal plating such as nickel plating or gold plating, and thereafter the metal plated-wiring lines has to be cut one by one by using a laser. Thus, there is another problem in that the process step becomes cumbersome, and the manufacturing cost is increased.
Furthermore, even when the wiring lines are directly formed on the glass board by way of the metal plating, there is another problem in that the fitting characteristic is deteriorated, and thus, the formed wiring lines may readily peel off from the glass board.
The present invention has been made to solve such problems, and therefore, has an object to provide a method of manufacturing a head chip, while manufacturing cost is reduced, and also a manufacturing step is simplified.
In order to solve the above problems, according to a first aspect of the present invention, there is provided a head chip in which: partition walls made of piezoelectric ceramic are arranged on two upper and lower sheets of a first board and a second board with predetermined intervals; chambers are defined between the respective partition walls; a driver voltage is applied to electrodes provided on side surfaces of the partition walls to change the capacity in the chambers; and the ink filled in the chambers is jetted from nozzle openings, characterized in that:
the first board and the second board are formed of a dielectric material, and also wiring lines, which are electrically conducted to the electrodes and elongated to the outside of the end portions of the partition walls in the longitudinal direction, are provided on the surface of either one of the first board and the second board; and
Further, the wiring lines include an inorganic conductive film as the lowermost layer and metal films formed thereon.
According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a head chip characterized in that the dielectric material is glass.
According to a third aspect of the present invention, in the first or second aspect of the present invention, there is provided a head chip characterized in that the inorganic conductive film is made of at least one sort of material selected from the group consisting of ITO, SnO2, ZnO, and ATO.
According to a fourth aspect of the present invention, in the first or second aspects of the present invention, there is provided a head chip characterized in that the inorganic conductive film is elongated between one of the first board and the second board and end portions of the partition walls in the width direction, and also end portion of the elongated inorganic conductive film in the width direction and the electrodes are electrically conducted to each other.
According to a fifth aspect of the present invention, in the fourth aspect of the present invention, there is provided a head chip characterized in that the thickness of the inorganic conductive film is set to be equal to or less than 3 xcexcm.
According to a sixth aspect of the present invention, in the first or second aspects of the present invention, there is provided a head chip characterized in that the electrodes and the metal films are formed by selective electroless plating.
According to a seventh aspect of the present invention, in the first or second aspects of the present invention, there is provided a head chip characterized in that the electrodes and the metal films are formed of a nickel layer and a gold layer.
According to a eighth aspect of the present invention, in the first or second aspects of the present invention, there is provided a head chip characterized in that a nozzle plate having the nozzle openings is provided at the end portions of the partition walls in the longitudinal direction, at which the chambers are opened, and also an ink chamber that communicates with the respective chambers is provided on the other end portion side of the partition walls.
According to a ninth aspect of the present invention, in the eighth aspect of the present invention, there is provided a head chip characterized in that the nozzle plate is formed of a dielectric material.
According to a tenth aspect of the present invention, in the first or second aspects of the present invention, there is provided a head chip characterized in that the partition walls are formed by jointing two sheets of piezoelectric ceramic having different polarization direction in the thickness direction.
According to a eleventh aspect of the present invention, in the first or second aspects of the present invention, there is provided a head chip characterized in that the regions corresponding to the chambers are provided with concave portions in one of the first board and the second board, which is provided with the wiring lines.
According to a twelfth aspect of the present invention, in the first or second aspects of the present invention, there is provided a head chip characterized in that a driver circuit is provided with the region corresponding to the wiring lines in one of the first board and the second board, which is provided with the wiring lines.
According to a thirteenth aspect of the present invention, in the first or second aspects of the present invention, there is provided a head unit characterized in that the head unit comprises the head chip as claimed in any one of claims 1 to 12 and a head holder that mounts the head chip.
According to a fourteenth aspect of the present invention, in the thirteenth aspect of the present invention, there is provided a head unit characterized in that the head holder may detachably hold an ink cartridge in which ink is stored.
According to the present invention, while the board made of the dielectric material is employed, the inorganic conductive film, that has the better fitting characteristic with the dielectric material, is provided at the lowermost layer of the wiring line.
As a consequence, the manufacturing step can be made simple, and also the manufacturing cost can be reduced. Moreover, the wiring lines can be easily conducted to the electrodes without fail.